The present invention is directed toward a fiber optic distribution system and more particularly to such a fiber optic distribution system capable of providing versatile and efficient service to its users.
Communication systems of the type contemplated by the present invention were initially established for transmission of various types of information including audio, video and digital data in the form of electrical signals through electrical transmission lines. Such information may of course comprise telephone signals, television signals, digital data, FM audio signals and the like. More recently, these electrical conductors have often been replaced by optical transmission systems where the information is transmitted through cables or the like formed from optical fibers.
The fiber optic cable may be in the form of one or more individual fibers or it may take the form of a bundle of many fibers. Here again, large numbers of fibers may be assembled in various types of sets such as ribbons each including flat arrays of, for example, 12 fibers. On the other hand, all or part of the fibers may be individually buffered, that is, contained within separate plastic tubes of relatively larger diameter to facilitate handling. In any event, fiber optical systems have become particularly desirable for such applications because of their bandwidth capabilities for handling greatly increased amounts of information, particularly in comparison with electrical transmission lines.
With the expanding use of such fiber optic systems, generally the same configurations of distribution networks have been employed for providing communication access of users as in earlier electrical communications systems. For example, service to large numbers of users in a given area, such as a city, a university or other complex, has been established with central offices or hubbing locations for providing service to groups of users in generally localized areas. A hubbing location commonly replaces a central office in localized areas such as universities and the like. The hubbing location is then interconnected with a central office by a trunk line for associating it with other communication networks. Accordingly, the term "central office" is used broadly in connection with the present invention and includes hubbing locations and other alternative means.
In order to provide service for each of these users from the central office, it has been common practice to provide dedicated lines between the central office and each given user through local networks in the form of conventional star or bus configurations, for example. With large numbers of users in a fixed location such as large buildings or portions of a university, large numbers of lines have been assembled in cables or the like to facilitate interconnection of all of the users with the central office.
At the same time, it has been of course necessary to provide for changes in the numbers and locations of such users within a given area. In the past, this was accomplished by shifting of dedicated lines from one user to another. Thus, where shifting patterns of users have occurred, it has often been necessary to reroute entire cables or portions of cables at very considerable expense.
A related problem concerns the need for assuring continuous service to users in the event of a loss of communications access, due for example to an interruption or break at a given location in a communication system or network. In order to provide redundant service to users upon request for overcoming this problem, it has also been common practice to provide separate dedicated lines for those users requesting redundant service. By arranging these separate lines along different routes, the user could thus be connected with the central office through one of the dedicated lines, communication access for that user being shifted to the other dedicated line through suitable switching equipment in the event of a loss of communication access in the first line. Naturally, the need for such redundant service further multiplies or increases the complexity of transmission systems providing communication access to large numbers of users.
With the increasing use of fiber optic transmission means, it has become possible to impose communications for large numbers of users upon single fibers through the use of conventional multiplexing equipment and the like. However, even with improvements in transmission capabilities made possible by such facilities, communications networks in congested areas such as large cities and the like have become increasingly complex and have necessarily employed relatively excessive amounts of networking cable.
Accordingly, there has been found to remain a need to provide improved distribution systems for communication access, particularly in the field of fiber optics, in order to provide improved services to groups of users in localized areas from central offices or the like while achieving versatility in service for accommodating changing numbers and patterns of users with existing fiber optic cables or the like while also facilitating the provision of redundant service for those users.